Battery backup system for fail-safe electric actuators

Abstract

A lithium-iron-phosphate battery backup system for use with an electric actuator. The battery backup system includes a controller for detecting a power failure and supplying backup power to the actuator to close a valve or damper connected to the actuator. The system can also detect out of range environmental conditions, and defects to the battery backup system. The battery backup system also includes a system for boosting the current and voltage of the batteries in the system.

We claim: 
     
         1 . An internal battery backup system for an electric actuator connected to a valve or damper having a housing with an internal cavity, the system comprising:
 a first Lithium-Iron-Phosphate cell configured for placement in the internal cavity of the actuator;   a control board coupled to the first Lithium-Iron-Phosphate cell having circuitry for sensing a fault condition and activating the first Lithium-Iron-Phosphate cell to provide power to initiate fail-safe positioning by the actuator.   
     
     
         2 . The internal battery backup system of  claim 1  further comprising a second Lithium-Iron-Phosphate cell configured for placement in the internal cavity of the actuator coupled to the control board. 
     
     
         3 . The internal battery backup system of  claim 1  wherein the control board is coupled to the mains power line providing power to the actuator. 
     
     
         4 . The internal battery backup system of  claim 3  wherein the control board is configured to sense a loss of power in the mains power line. 
     
     
         5 . The internal battery backup system of  claim 4  wherein the control board activates the first Lithium-Iron-Phosphate cell when a loss of power is sensed in the mains power line. 
     
     
         6 . The internal battery backup system of  claim 1  wherein the control board is coupled to a temperature sensing device. 
     
     
         7 . The internal battery backup system of  claim 6  wherein the control board is configured to compare a temperature reading from the temperature sensing device with a set limit temperature range and to provide a signal if the temperature reading is outside the set limit temperature range. 
     
     
         8 . The internal battery backup system of  claim 1  wherein the control board is configured to determine a voltage level of the first Lithium-Iron-Phosphate cell and to provide a signal if the voltage level of the first Lithium-Iron-Phosphate cell falls below a set limit. 
     
     
         9 . The internal battery backup system of  claim 2  wherein the first Lithium-Iron-Phosphate cell and the second Lithium-Iron-Phosphate cell are coupled in parallel. 
     
     
         10 . The internal battery backup system of  claim 1  wherein the control board is coupled to field control system. 
     
     
         11 . The internal battery backup system of  claim 1  wherein the control board includes a charging circuit and a discharge circuit. 
     
     
         12 . The internal battery backup system of  claim 11  wherein the control board includes to a voltage boost system. 
     
     
         13 . The internal battery backup system of  claim 1  wherein the control board is coupled to an end-of-travel switch. 
     
     
         14 . The internal battery backup system of  claim 13  wherein the control board de-actives the first Lithium-Iron-Phosphate cell when the control board senses activation of the end-of-travel switch. 
     
     
         15 . The internal battery backup system of  claim 12  wherein a direct current voltage from the first and second Lithium-Iron-Phosphate cells is directed through an inductor to a capacitor in the voltage boost system. 
     
     
         16 . The internal battery backup system of  claim 15  wherein the voltage boost system includes a MOSFET gate that enables current to flow through the inductor to ground when the boost system is in a drain phase. 
     
     
         17 . The internal battery backup system of  claim 16  wherein the MOSFET gate enables current to flow through the inductor to the capacitor when the boost system is in a charge cycle. 
     
     
         18 . An internal battery backup system for an electric actuator comprising:
 a first Lithium-Iron-Phosphate battery pack containing a first Lithium-Iron-Phosphate cell and a second Lithium-Iron-Phosphate cell; and,   a power and management unit connected to the first Lithium-Iron-Phosphate battery pack configured to charge the cells in the Lithium-Iron-Phosphate battery pack from a mains power supply and to discharge the cells to the electric actuator upon sensing a fault condition in the mains power supply.   
     
     
         19 . The internal battery backup system of  claim 18  further comprising a second Lithium-Iron-Phosphate battery pack containing a first Lithium-Iron-Phosphate cell and a second Lithium-Iron-Phosphate cell connected to the power and management unit. 
     
     
         20 . The internal battery backup system of  claim 18  further comprising a boost system in the power and management unit which directs current from the cells in the first Lithium-Iron-Phosphate battery pack through a capacitor to provide a voltage to the actuator greater than a voltage of the battery pack.